Table tennis ball



D. C. MABEE Aug. 31, 1937.

TABLE TENNIS BALL Filed April 17, 1936 ME U JazzalC-Jfafie e PatentedAug. 31, 1937 UNITED smrss ATENT OFFHCE Claims.

My invention relates to a new and improved ball to be used in playingthe game known as table tennis. The table tennis balls now in use aremade of Celluloid or similar material. They are made in hollow sphericalform, each half of the ball being formed separately. The halves thusformed are joined together along a circumferential seam.

The material forming the wall of the ball,

6 which is a hollow sphere, must be thin in order to make a ball oflight Weight. Balls of light weight are preferred by the moreexperienced players.

- In the table tennis balls of the prior art, this effort toreduce theweight, combined with the necessity for making the balls in sections,joined along a circumferential seam, has resulted in producing ballswhich are not uniform in weight distribution, are not uniform in shape,and the surface does not present a uniform resistance, with the resultthat the movement of the ball through the air, after it has been hitbythe player, is variable, depending upon which portion of the ball hasbeen struck by the paddle.

A further disadvantage of the present ball is that when the playerstrokes the ball with his paddle, the effect of his stroke will vary,dependent upon whether the paddle hits the ball on or near thesean'nwhere, because of the double 1 thickness of the wall of the ball,the surface offers substantial resistance, or he hits the ball at apoint on the surface farther away from the seam, where the resistance ismaterially less.

The primary object of my invention is to overcome this variation inresilience of the surface of the ball, and, by strengthening the weakeror unseamed portions of the surface, without materially increasing theweight, to provide a ball which will react uniformly to the stroke ofthe paddle.v

Another object of my invention is to provide a ball in which, by theaddition of material in the portions of the ball away from the seam, theball can be more evenly balanced. A materially improved ball will resultfrom the accomplishment of my primary object, even though this desiredsecond object be not incorporated in it,,.but it is preferable that bothobjectives be realized.

50 A further object of this invenion is to provide an improvement in.the game of table tennis which comprises the provision of .a tabletennis ball which is of substantially the same weight as theconventional ball but which is more uni- 5 formy balanced and rigidifiedandthe strength of which is predetermined so as to be ample to resistthe impact force of a paddle striking the same irrespective of theposition of the ball or the angle of the path of the ball with regard tothe striking surface of the paddle.

Another object of the invention is to provide a dynamically balancedtable tennis ball presenting a uniform outer or striking surface.

In order to accomplish the foregoing objectives, I have invented the newand novel constructions of the ball which will now be set forth.

In the drawing:

Figure 1 shows the ball, in finished form, as it will appear.

Figure 2 is an enlarged fragmentary sectional view taken as indicated bythe line II-II in Figure 1.

Figure 3 is an elevational view taken as indicated by the line IIIIII inFigure 2.

Figure 4 is a fragmentary sectional view taken through a rib adjacentthe seam of the ball shown in Figures 2 and 3.

Figure 5 is a view similar to Figure 3 but showing a modified form ofreinforcement.

Figure 6 is a fragmentary developed view of another form ofreinforcement.

Figure 7 is a view similar to Figure 2 but showing another form of theinvention.

Figure 8 is a view, in cross. section, of dies which may be used in themanufacture of the ball of my invention.

In Figure 1 the finished ball is shown as. viewed from the outside. Sofar as outside appearance is concerned it may look just like theregulation or usual table tennis ball heretofore in use, or it may havea uniformly rough or any other appearance desired. It is. spherical inshape and is hollow. The two halves, I and 2, have been formedseparately and have been joined together along the seam 3.

In Figure 2, the thin shell like construction of of the ball is shown.The thin material forming the wall of the ball is shown at 4. Where thetwo halves of the ball are joined together at the seam, 3, it will beseen that the wall of the ball has an increased thickness. Thisincreased thickness along the seam takes the form of an equatorial band.The weight is materially increased along this band.

The double or otherwise increased thickness along this band also givesgreater strength along the band, and, unless the supporting ribs areused as herein disclosed, the resilience of the ball will vary over itssurface. When struck by the player 55 at points along or adjacent tothis band, such as indicated by the arrow A, the surface supportingeffect of the seam will provide comparatively greater rigidity than if aball, not possessing the advantages of my invention, is struck at thepoints indicated by the arrow B, for example.

In the balls of the prior art, this difference in surface resiliency isso great that balls which have been hit with great force at points suchas indicated by the arrow B, have had this portion of the wall driveninward, in which condition the wall of the ball remained, thus causingthe ball to move through the air in an erratic manner and rendering theball useless.

I propose to overcome these faults in the prior art balls bystrengthening the unseamed portions. In accordance with the invention, Iform ribs on the inside of the wall of the ball to give the portions ofthe wall away from the seam a rigidity substantially greater than suchportions of the wall would otherwise have and approaching more nearly tothe rigidity of the ball along the seam 3.

In Figures 2, 5, 6, and 7 I have shown different forms ofreinforcements.

In Figure 2, I have shown reinforcing ribs as beginning a short distanceaway from the seam 3. It would not be a departure from my invention tobegin the ribs at the seam, but I prefer to have the ribs begin slightlyaway from the seam as at S, in order to avoid adding any more rigidityalong the seam. The seam adds sufficient rigidity to support the surfacefor a short distance on each side of it.

Beginning at 5 on the inside surface of the wall of the ball, the ribs 5gradually increase in height until a point farthest away from the seamis reached, such as at "i. Each rib will have its greatest strength atthe point where that rib is farthest away from the seam of the ball and,from that point of greatest height the rib will taper off toward theseam so that, before it reaches the seam of the ball, it will havedisappeared.

In my preferred form, the ribs will be so constructed that the points inthe wall of the ball farthest from the seam will receive the greateststrengthening effect from these ribs and that this strengthening effectwill gradually diminish as the seam is approached.

The ribs may be reduced in height because the rigidifying effect of theseam 3 on the adjacent parts, A, of the ball will diminish toward thepoints B of maximum distance from the seam, and the combined effect ofribs and seam is that of a substantially uniform strength distribution.

These ribs can be moulded from a sheet of uniform thickness which isbeing used to make the ball. In such case, the wall portion 8 remotefrom the seam 3 may be thinner than the portion at A, adjacent the seambut the strengthening eifect of the ribs will more than offset anyweakness. In this way, the ball of my invention can be made without anyincrease in weight over the balls now in use.

However, if desired, the ribs which I have shown can be made wholly orpartially of additional material, so as to leave the wall of the ballthe same thickness at 3 as at A, or of only slightly less thickness. Inthis way the ball can be better balanced-the added weight in the ribsserving to balance and offset the added weight along the seam.

In Figure 5 the ribs 9 and in Figure 6 the ribs iii are in anarrangement somewhat different from each other and from that appearingin Figures 2, 3, and 4.

In Figures 2, 3, and 4 the ribs are disposed in right angularly relatedplanes substantially parallel to similarly related diametral lines ofthe seam. In Figure 5 the ribs are disposed along arcs of great circlesof the ball. In Figure 6 the ribs are arranged in a multiple diamondformation. The number and arrangement of ribs may be varied as desiredwithin the principles of the invention. The ribs could be of uniformheight if desired, or may vary in height.

Figure 7 shows a reinforcement construction by which the result achievedby ribs may be obtained without resorting to the use of ribs. In thisform, the sections through the axis of the seam may be substantiallyidentical, 1. e., with the thickness at each pole of the ball increasedas at I I and gradually diminished uniformly to the area A adjacent theseam 3. This could be effected by molding or in any other suitable waypreferably from a sheet of uniform thickness.

The thickness at H may be as great as at the seam 3 if desired.

The ball of my invention can be pressed from sheet material by diesshaped to form this sheet material into hollow hemispherical portions,adapted to be joined together to form a complete sphere. The female diecan have a smooth forming surface so as to provide an outer smoothsurface for the ball.

The inner, or male die, can have depressions in the forming surface,adapted to form the strengthening ribs of my invention upon the innersurface of the wall of the ball.

I have illustrated such dies in Figure 8. In this figure, i2 is thefemale die, and I3 is the male die. Both are shown in cross-section. AtI 4, in the male die member, I have shown one of the rib formingdepressions. These rib forming depressions can be multiplied andarranged upon the forming surface of the male die as desired.

The sheet material is pressed between these two die members. Thematerial to form the wall of the ball is caused to be in a condition toflow and accept a set and form impressed upon it by the dies, by theapplication of heat, if necessary,

or by other known means adapted to place the particular material used ina condition to flow and to receive a shape and form impressed upon it bythe dies and to retain that shape and form upon removal from the dies.

The dies are then separated, the formed and shaped section of the wallof the ball is removed from the dies, and then joined, in waysheretofore well known, to another section or sections to form the ballof my invention.

Any unevenness at the seams, appearing upon the outer surface of theball may then be removed by any means. heretofore well known and nowbeing used in the manufacture of table tennis balls, and the ball isthen ready for use.

It will be evident to those skilled in the art that, if desired, thematerial to be used in forming the wall of the ball need not be insheet'form, so long as it is in a condition to fiow, to accept and toretain the shape and form impressed upon it by the dies.

In actual use, the ball of my invention is greatly superior to any tabletennis balls heretofore in use. When the player strokes the ball of myinvention with his paddle, he will get a substantially uniform result,regardless of whether his paddle contacts the ball at one point or atanother point on the surface of the ball, and regardless of whether hehits the ball directly to drive it Without imparting spin to it, orstrokes the ball at an angle tangential to its surface, toimpart spin tothe ball.

When the player is careful to hit the ball exactly the same way insuccessive strokes, he will get exactly the same result, asdistinguished from the variety of results which are obtained by use ofany of the table tennis balls heretofore in use. The use of a ball madein accordance with my invention will add much to the game of tabletennis by making uniformity and accuracy possible, and by eliminatinguncertainty as to how the ball will perform even though it be hitperfectly.

The table tennis balls heretofore in use have been made of thinresilient material of uniform thickness. When made of such material, ithas been very difficult to secure balls of uniform and true sphericalshape. By the time such balls reach the user, many of them will be foundto have assumed shapes other than true spheres.

shape, or lop-sided, as the and supporting means At the point where thesections have been joined together, because of the added strength alongthe seam, that portion has a tendency to retain the intended truespherical contour, but the portions away from the point of juncture ofthe sections, have a pronounced tendency to become irregular in shapeand cause the ball to become other than a true sphere.

This tendency of the ball to become untrue in users commonly term it, isovercome to a substantial degree by manufacturing them in accordancewith my invention.

In the ball of my invention,'the strengthening employed at points otherthan at the juncture of the sections, not only provides a ball which isuniform in balance and resistance, but also provides a ball which isuniform in shape and which will have a greater 40 tendency to retain theshape of a true sphere.

tennis ball The exact arrangement and character of the strengthening andsupporting elements may be varied as good engineering practice andexperience may dictate, without departing from my invention, and it isnot my intention to limit myself to the specific measurements,arrangements or proportions of the parts as shown.

I claim as my invention:

1. As an article of manufacture, a hollow table made of relatively thinflexible Celluloid or similar material comprising a plurality ofsections joined together by a circular rein-- forcing seam ofpredetermined rigidity, each of said hollow sections being internallydeformed in such a manner as to provide reinforcements of such characteron opposite sides of the seam as to compensate for increased rigidity atthe seam and to cause said sections to have substantially the samerigidity as the seam, so that said ball is of substantially uniformflexibility throughout its spherical surface.

2. A hollow table tennis ball made of relatively thin flexible Celluloidor similar material comprising a plurality of sections joined by acircular reinforcing seam, portions of each section spaced away fromsaid seam being formed with reinforcing ribs of such character as toprovide said sections of the ball on diametrically opposite sides ofsaid seam with rigidity comparable with that afforded by said seam, sothat the ball has substantially the same degree of rigidity throughoutits spherical surface.

3. A hollow table tennis ball made of relatively thin flexible Celluloidor similar material com,- prising a plurality of sections joined by acircular seam, each of said sections being formed with a reinforcingthickened portion leading away from the seam and of such area andcharacter as to compensate for the increase in rigidity imparted to theball by the seam and thus to provide the ball with substantially thesame rigidity throughout the spherical wall of the ball.

4. A hollow table tennis ball made of relatively thin flexible Celluloidor similar material comprising a plurality of sections joined togetherby a seam, each of said hollow sections being provided with means forcompensating for the increase in rigidity imparted to the ball by theseam, which means is provided by a thickened wall in each section whichincreases in depth radially outward and away from said seam, saidprogressively thickened portion being on the interior of the ball and ofsuch character as to cause the exterior spherical surface of saidsections on opposite sides of the seam to have substantially the samerigidity throughout as that provided at the seam.

5. As an article of manufacture, a hollow table tennis ball made ofrelatively thin flexible Celluloid or similar material. comprising aplurality of sections joined together by a circular reinforcing seam ofpredetermined rigidity, each of said hollow sections being internallydeformed in such a manner as to provide reinforcements of such characteron opposite sides of the seam as to compensate for increased rigidity atthe seam and to cause said sections to have substantially the samerigidity as the seam, so that said ball is of substantially uniformflexibility throughout its spherical surface, said reinforcements beingdisposed on the interior surface of the ball and being so located and ofsuch extent as to cause the weight of diametrical portions of the ballwall on oposite sides of the seam to be in balance with that of theseam.

' DANIEL C. MABEE.

